Exploring the role of physical activity in maintaining health through DNA repair, thyroid cancer prevention, and obesity-specific quality of life

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Beresford, Shirley A.A.

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Cash, Stephanie Whisnant

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2012-09-13T17:22:28Z

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2015-12-14T17:55:47Z

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2012-09-13

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2012

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Cash_washington_0250E_10073.pdf

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http://hdl.handle.net/1773/20535

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Thesis (Ph.D.)--University of Washington, 2012

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<bold>Background</bold>. Regular physical activity has an abundance of physical and mental health benefits; however much remains to be elucidated about the benefits of long-term versus short-term activity for cancer prevention, potential mechanisms linking activity and cancer prevention, and the relationship between activity and quality of life. The goal of this research was to investigate these questions and contribute to the understanding of the role of physical activity in maintaining health across the life span.<bold>Methods</bold>. . The association between long-term physical activity and risk of papillary thyroid cancer was investigated among 116,939 women in the California Teachers Study (CTS) using Cox proportional hazards regression to estimate relative risks (RRs) and 95% confidence intervals (CIs). Recent physical activity was examined in relation to DNA damage and repair among 122 healthy, older participants in the Vitamins and Lifestyle (VITAL) cohort validation sample using linear regression to estimate beta coefficients and 95% CIs. Finally, associations of physical activity and sedentary behavior with log-transformed obesity-specific quality of life (QoL) scores were investigated among women in The Socioeconomic Status and Obesity (SESO) Study using linear regression to estimate back-transformed geometric means and 95% CIs. All analyses additionally examined the role of body mass index (BMI) in associations. <bold>Results</bold>.Long-term physical activity was significantly associated with a reduced risk of papillary thyroid cancer in the CTS only for normal-weight women (BMI<25 kg/m2). Recent physical activity was significantly positively associated with 60-minute DNA repair among VITAL participants, even when adjusting for BMI. Physical activity was significantly positively associated with obesity-specific QoL scores in the SESO Study to varying degrees among Non-Hispanic White (NHW), English-speaking Hispanic (ESH), and Spanish-speaking Hispanic women. Sedentary time was significantly negatively associated with obesity-specific QoL for NHW and ESH women. Many observed associations were attenuated or accounted for when additionally adjusting for dietary behaviors or BMI. <bold>Discussion</bold>. Results indicate that physical activity is beneficial for thyroid cancer prevention, DNA repair, and obesity-specific QoL. Additional longitudinal analyses are needed to assess the long-term benefits of increasing physical activity levels and to parse out mechanisms and potential subgroup differences.